1. Field of Invention
The present invention relates to a structure of foldable optical path. More particularly, the present invention relates to a structure of foldable optical path inside the scanning module of a charge couple device (CCD) type optical scanner.
2. Description of Related Art
With the progress in multimedia technology, the improvement of processing of image data promoting the development of computer peripheral device such as scanner. From handheld monochrome type to present full color and high-resolution type, the scanner can produce a finer and vividly image. Today, a scanner is a widely used computer peripheral device for capturing document image and converting the document image to digital signals for computer process.
The optical system 100 of the conventional optical scanner as illustrated in FIG. 1 has a light source 110, a reflection mirror set 120, an image-formation set 130, and an optical sensor such as a charge couple device (CCD) 140. While performing scanning, light from the light source 110 is incident onto a document 300 putting on a light transmissible plate 200 to obtain an image light 310 by reflection or transmission. The reflection mirror set 120 comprises several reflection mirrors 121, 122, 123 and is located in an optical path of the image light 310. The image of document 300 on the light transmissible plate 200 is directed to the reflection mirror set 120 and reflected to the image-formation set 130, such as a lens set, by the reflection mirror set 120. The image-formation set 130 can receive the image light 310 of the document 300 transmitted by the reflection mirror set 120, focuses and projects the image light 310 onto the charge couple device 140. The above-mentioned is the optical path of the image light 310 of the document 300 transmitting in the optical system 100 of the optical scanner.
The charge couple device mentioned above transfers the light into photoelectric current by photoelectric transformation and saves the current in a storage electrode to convert into a signal charge, then converts the charge into different potential differences. The optical scanner utilizes these different potential differences to form the different bright and dark level, then displays the image by the gray scale light.
Furthermore, CCD is one kind of semi-conductor IC devices and manufactured by semi-conductor process. CCD""s resolution won""t be affected by the manufacture easily. However, the length of the CCD is much shorter than the width of normal documents or pictures, it needs to utilize a image-formation set to reduce the scale of the image when scanning, in order to scan the full image. Thus the size of the system will be larger, and it wastes time of fabricating and adjusting.
Contact image sensor (CIS) is another type of linear scanner commonly used for scanning an image or a document. The image or document is captured in an electronic format for ease of storage, display, processing and transmission. Due to a modular design, the CIS is easy to assemble, light, compact and costs less to produce. FIG. 2a is a front view of the scanning module of a conventional contact image sensor and FIG. 2b is a cross-sectional view of the scanning module. As shown in FIGS. 1a and 1b, a conventional contact image sensor (CIS) 400 consists of a linear light source 404, a self-focus lens array 401 and a sensing array 402 over a substrate board 403. The light source 404, the self-focus lens array 401, the sensing array 402 and the substrate board 403 are mounted on an aluminum frame 405. In a scanning operation, the self-focus lens array 401 reflects light coming from the original document 300 and forms an image on the sensing array 402. The sensing array 402 converts the color or the gray step level of a line of the document 300 into electronic signals. Throughout the scanning session, the scanning surface of the scanning module 400 in constant contacts with a document platform 210, and the document 300 is pulled forward or backward by a roller 500 for scanning.
The self-focus lens array 401 is constructed of a row of small-caliber radial gradient index lens, wherein the refractive index of each lens varies along the radial direction gradually, thus the lens are able to format a image. The whole lens array can format the image of one line of the original document on the sensing array in a ratio of 1:1. Compared with CCD which uses a normal image-formation set to format a image, the advantages of CIS which uses the self-focus lens array to format the image are the shorter optical path and the thinner and lighter applied system. However, the disadvantages of CIS are the depth of field is short, and the mechanical design and the control of the system need to be more precise than CCD.
As a conclusion, the advantages of the optical scanner which uses CIS are small-size and able to be portable, but its disadvantage is the depth of field is short, thus it""s difficult to get a clear image when scanning a uneven document or picture. The advantages of the optical scanner which uses CCD is the longer depth of field, but its disadvantage is the mechanical design of the system can""t be compact, thus it""s not convenient to carry it. Moreover, since the document must be put on the light transmissible plate of the CCD type optical scanner while scanning, so it""s not convenient in operation when scanning a thick book or large-size newspapers or magazines. Although some small-size flatbed scanners are able to put on a book or large-size newspapers or magazines to scan downward, but a user ought to hold the whole scanner during the scanning operation. Even the scanning result of the early-phase hand-held scanner is easy to be affected by operation cause it needs a user to push the scanner by hand to proceed the scanning operation.
Accordingly, one object of the present invention is to provide a structure of foldable optical path that can be use in the optical scanners of a CCD type or a type of non-contact imaging sensor. The structure of foldable optical path arranges part of the optical path in a foldable packing device, thus the scanner is able to utilize normal lens with better depth of field and makes the scanner more compact for the convenience of operation and carrying. A user doesn""t have to push the scanner to proceed the scan operation. After the foldable packing device is folded, it""s able to save the cost of package and storage because the volume of the scanner is decreased.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides a structure of foldable optical path for an optical scanner. The optical scanner at least having a main frame, a light transmissible plate, a light source, a reflection mirror set, an image-formation set, and an optical sensor. The light source illuminates a document to get an image light. The reflection mirror set is arranged in an optical path of the image light to direct the image light to the optical sensor. The image-formation set is arranged in the optical path between the reflection mirror set and the optical sensor. The document contacts with the light transmissible plate during scanning. The structure of foldable optical path comprises as follows.
A foldable packing device is coupled to the main frame by a rotation pivot axis. The foldable packing device is able to rotate from a first position, at which the scanner is under a scanning operation, to a second position, at which the foldable packing device is folded via a pivot axis. Wherein the image-formation set and the optical sensor are disposed in the interior of the foldable packing device. While the foldable packing device is at the first position, the optical path of the image light will be directed into the interior of the foldable packing device through the image-formation set to the optical sensor. While the foldable packing device is at the second position, the image-formation set and the optical sensor diverge from the optical path of the image light.
The invention also provides an optical scanner for scanning a document. The optical scanner comprising: a main frame, a foldable packing device, a light source, a reflection mirror set, an optical sensor, and an image-formation set.
The main frame has a light transmissible plate, and the document contacts with the light transmissible plate. The foldable packing device connects to the main frame, and the foldable packing device is able to rotate from a first position which the scanner is during a scanning operation to a second position which the foldable packing device is folded via a pivot axis.
The light source is disposed in the interior of the main frame and illuminating the document to get an image light, wherein the image light has an optical path.
The reflection mirror set is disposed in the optical path and in the interior of the main frame, the reflection mirror set reflects the image light.
The optical sensor is disposed in the interior of the foldable packing device, while the foldable packing device is at the first position, the optical path of the image light will be directed into the interior of the foldable packing device to the optical sensor, while the foldable packing device is at the second position, the optical sensor diverges from the optical path of the image light.
The image-formation set is disposed in the interior of the foldable packing device, while the foldable packing device is at the first position, the optical path of the image light will be directed into the interior of the foldable packing device through the image-formation set to the optical sensor, while the foldable packing device is at the second position, the image-formation set diverges from the optical path of the image light.
The reflection mirror set has a plurality of reflection mirrors. The reflection mirror set is able to move in the interior of the main frame during the scanning operation, and distances between the reflection mirrors are adjustable. Thus a distance from the document to the image-formation set can be fixed. The optical scanner further includes a transmission member connecting to the reflection mirror set and drives the reflection mirror set moving in the interior of the main frame.
The reflection mirror set and the image-formation set are able to move in the interior of the main frame during the scanning operation. Thus the distance between the reflection mirror set and the image-formation set and the distance between the optical sensor and the image-formation set are adjustable in order to maintain the same magnification of the image light through the image-formation set to the optical sensor. The optical scanner further includes a transmission member connecting to the reflection mirror set and the image-formation set, and drives the reflection mirror set and the image-formation set moving in the interior of the main frame separately.
The optical scanner further includes a switch disposing near the pivot axis used to detect whether the foldable packing device is at the first position or not. Moreover, a calibration chart that disposing on the light transmissible plate used to calibrate the optical scanner while power is on.
One major aspect of this invention is the utilization of a foldable packing device for the convenience of carrying and operation. A user don""t have to push the scanner to proceed the scanning operation.
Another aspect of this invention is deposing part of the optical path in the interior of the foldable packing device, and the foldable packing device is able to be folded to reduce the cost of the package and storage.
Another aspect of this invention is utilizing of a CCD that collocates with a normal image-formation set to get a better depth of field.
Another aspect of this invention is deposing a switch near the pivot axis to detect the position of the foldable packing device and prevent the foldable packing device from being folded during the scanning operation or check whether the foldable is at the right position or not.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.